Can I replace the rear fender well on my class A ?

It's best just to prevent the blowout in the first place, monitor closely, and take it like a man if it does happen to you.

Course I've never been one to want the (government--- shhhh!) to seal me in a rubber cubicle either.

The prime causes of blowouts are improper inflation or overloading.
Both easily preventable.
Don't overload. determine your proper air pressure and stick to it. Actually physically inspect your tires every once in a while (this does require getting down in the mud and crawling under your motorhome.)

Do as much as is reasonable prevention in your opinion.
You still cannot prevent everyone, it will happen someday.

I read a lot on here about the damage from a blowout. Does anyone make a reinforced surround for a wheel well? I was thinking maybe a 3/8 in thick fiber glass reinforced epoxy or a rubber material surround might contain the blow out.

I feel ya man. I had a blowout two years ago and it damaged my steel wheel well. I had a small split on the weld that from the vertical to the horizontal pieces. The crack was small and under the bathroom cabinet where it would be very difficult to weld back together. I have a MIG welder but, decided on the redneck fix. I put some eternabond tape on the crack on the inside of the wheel well. It works great and doesn't leak at all. I'm not recommending that you do that. I'm just saying that on my steel well with a small split it worked. Blowouts on RV's suck. That's why I run American made tires -- now.

Shouldn't be too difficult for an inner fender. Doesn't have to look pretty but water proofing is a must. The hard part is finding the right material. Has to stand up to what ever the tires may pick up and throw at it. if you can find the right material shouldn't be a very difficult weekend project.

The diamond plate idea is worth considering. Plastic is easier but you will need to find the correct material. Certain plastics will become very brittle in cold weather and one good size stone will shatter or crack it.

Assuming your talking about the outside portion panel around your tire. Not sure what year you have, but looking at some pics of your model it appears you have similar panels as mine. You should be able to remove the panel and replace it. I had to remove one of mine and reattach with better screws. That entire piece on mine was pretty easy to remove and re-install.

Get some diamond plate and bolt it in place